[Interpreter] Make ForInPrepare take a kRegTriple8 and ForInNext take kRegPair8 for cache state

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/bytecode-register-allocator.h"
 #include "src/interpreter/control-flow-builders.h"
@@ skipping 803 matching lines @@
   BytecodeLabel subject_null_label, subject_undefined_label, not_object_label;
 
   // Prepare the state for executing ForIn.
   VisitForAccumulatorValue(stmt->subject());
   builder()->JumpIfUndefined(&subject_undefined_label);
   builder()->JumpIfNull(&subject_null_label);
   Register receiver = register_allocator()->NewRegister();
   builder()->CastAccumulatorToJSObject();
   builder()->JumpIfNull(&not_object_label);
   builder()->StoreAccumulatorInRegister(receiver);
-  Register cache_type = register_allocator()->NewRegister();
-  Register cache_array = register_allocator()->NewRegister();
-  Register cache_length = register_allocator()->NewRegister();
-  builder()->ForInPrepare(cache_type, cache_array, cache_length);
+
+  register_allocator()->PrepareForConsecutiveAllocations(3);
+  Register cache_type = register_allocator()->NextConsecutiveRegister();
+  Register cache_array = register_allocator()->NextConsecutiveRegister();
+  Register cache_length = register_allocator()->NextConsecutiveRegister();
+  // Used as kRegTriple8 and kRegPair8 in ForInPrepare and ForInNext.
+  USE(cache_array);
+  builder()->ForInPrepare(cache_type);
 
   // Set up loop counter
   Register index = register_allocator()->NewRegister();
   builder()->LoadLiteral(Smi::FromInt(0));
   builder()->StoreAccumulatorInRegister(index);
 
   // The loop
   loop_builder.LoopHeader();
   loop_builder.Condition();
   builder()->ForInDone(index, cache_length);
   loop_builder.BreakIfTrue();
-  builder()->ForInNext(receiver, cache_type, cache_array, index);
+  DCHECK(Register::AreContiguous(cache_type, cache_array));
+  builder()->ForInNext(receiver, index, cache_type);
   loop_builder.ContinueIfUndefined();
   VisitForInAssignment(stmt->each(), stmt->EachFeedbackSlot());
   Visit(stmt->body());
   loop_builder.Next();
   builder()->ForInStep(index);
   builder()->StoreAccumulatorInRegister(index);
   loop_builder.JumpToHeader();
   loop_builder.EndLoop();
   builder()->Bind(&not_object_label);
   builder()->Bind(&subject_null_label);
@@ skipping 1323 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8